This disclosure generally relates to the monitoring of hydrocarbon wellbores, and more particularly to detecting mud pulses using Distributed Acoustic Sensing (DAS) techniques.
Drilling is exceedingly more complex than merely boring a hole in the ground. Modern drilling relies on the acquisition of many disparate data streams, some of which may be obtained using mud pulse telemetry techniques. Highly engineered drilling fluid (known in the industry simply as “mud”) must be constantly circulated downhole through the drill bit and the area surrounding the drill bit for cooling, lubrication, and removal of cuttings, and then pumped through a mud conditioning system to clean the drilling fluid or to perform other operations. That same mud may simultaneously serve as the signal propagation medium for communicating signals to the surface from thousands of feet below. With mud pulse telemetry, drilling systems may use valves to modulate the flow of the mud, which may generate pressure pulses that propagate up the column of fluid inside the wellbore. The pressure pulses may be referred to as mud pulses, and may be analyzed to determine one or more properties or characteristics associated with the drilling operation.
Acoustic sensing using DAS may use the Rayleigh backscatter property of a fiber's optical core and may spatially detect disturbances that are distributed along the fiber length. Such systems may rely on detecting optical phase changes brought about by changes in strain along the fiber's core. Externally-generated acoustic disturbances may create very small strain changes to optical fibers.
While embodiments of this disclosure have been depicted and described and are defined by reference to example embodiments of the disclosure, such references do not imply a limitation on the disclosure, and no such limitation is to be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and not exhaustive of the scope of the disclosure.